[2.11] OBJ model format

[stgatilov]

The latest dev build (dev16629-10139) supports Wavefront OBJ format for static models.

Some details:

1. Model must consist only of triangles. Quads/polys will produce warnings and won't work properly. NURBS/lines/etc are ignored.
2. Normals and texcoords are mandatory for all triangles, otherwise model loading will fail.
3. Widely used extension for RGB vertex colors is supported (standard OBJ does not support vertex colors).
4. TDM materials are referenced by "usemtl textures/test_obj/rock". Standard MTL files are not supported yet.

Unlike LWO and ASE imports, which try to automatically merge close vertices, no postprocessing is done for a model in OBJ format.
As far as I understand, it means less suffering with smoothing groups for instance.
Also it means that loading OBJ model is very fast, even for a large model.
The only downside thus far is that zipped LWO file can be smaller than zipped OBJ, but I don't have exact numbers yet (I'd be happy if someone can help me with it).

Speaking of OBJ format, there are several pending questions:

1. Should we support MTL format (common subset) in TDM engine? Or as import plugin in DarkRadiant?
2. Should we support referencing part of OBJ file as model in TDM map? Is it common to export several LODs into one OBJ?

[Dragofer]

I've opened a ticket to ask for .obj model render support to be added to DR so this can catch on better. Support for a universal model format is very significant when obtaining models from online repositories.

On 10/23/2022 at 8:39 PM, stgatilov said:

Should we support referencing part of OBJ file as model in TDM map? Is it common to export several LODs into one OBJ?

I'm not sure - the ideal would be if models automatically switched to LOD versions if any are available, and if the stages are in the same file this would be easier to achieve. But I think it's still going to require entityDefs with hand-calibrated distance values.

Could still be convenient, the same way how having the shadowmesh and collisionmesh in the same model file is more convenient than having a _cm file somewhere nearby.

[stgatilov]

OBJ does not have anything like LOD info in the format.
It only allows aplitting geometry into groups/objects of different names.
Putting all the LOD settings into OBJ is barely possible.

Maybe it is possible to use defaults in such case, but wouldn't it be better to implement some Blender export or DarkRadiant import for such case (i.e. that would create entityDef automatically) ?